What does the term "nominal sizes" refer to?

The term "nominal sizes" refers to size approximations in the context of pipe fitting and plumbing. Nominal sizes are used to designate the size of pipes and fittings but do not correspond to the actual physical measurements. For instance, a pipe described as 2 inches nominal size may not measure exactly 2 inches in diameter. Instead, the nominal size serves as a label or shorthand that identifies a specific category of size that is accepted within the industry for ease of identification and compatibility.

Using nominal sizes helps simplify communication among professionals in the field, allowing them to understand what type of fittings, joints, and other components will work together, even if the actual dimensions vary slightly due to manufacturing tolerances. This classification system is crucial in ensuring consistent performance and functionality in plumbing systems.